Systems and methods for restoring blood flow to a vessel

ABSTRACT

In one illustrative embodiment, a thrombectomy device is disclosed. The thrombectomy device includes a treatment portion, comprising a reversibly-expandable framework configured to be deployed from within a microcatheter into a selected vasculature for removing thrombus or embolus. The thrombectomy device further includes a substantially tubular connection member disposed on a proximal end portion of the treatment portion configured to receive a terminal portion of a delivery member for positioning the treatment portion within the vasculature. The framework includes structural features for engaging the thrombus or embolus including one or more of: framework peaks and valleys along a long axis of the treatment portion or a plurality of strut members.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 61/811,689, filed on Apr. 12, 2013, the entirecontents of which are incorporated by reference in their entirety as iffully set forth herein.

TECHNICAL FIELD

This disclosure relates to systems and methods for removing blockages,e.g., embolus or thrombus, to restore blood flow in the vasculature ofan organism. In particular, thrombectomy devices and methods for theiruse are disclosed.

BACKGROUND

Acute ischemic stroke is one of the major sources of morbidity andmortality in the industrialized countries. In the USA, approximately795,000 patients experience a stroke every year. Intravenouslyadministered tissue plasminogen activator (IV tPA) has been shown toimprove patient outcome. However, the time window for treatment and therecanalization rate of this approach are limited, and the application ofthrombolytic drugs increases the risk of symptomatic intracranialhemorrhage. The success of recanalization, furthermore, depends on theocclusion site.

Mechanical recanalization techniques, i.e., mechanical thrombectomydevices can accelerate the process of recanalization, increase therecanalization rate, and even expand the window of opportunity. Somein-use mechanical thrombectomy devices generally fall into threecategories: 1) devices including a filter trap designed and built tocollect and remove embolus; 2) a cork-screwed guidewire like device toretrieve embolus; and 3) a stent like device connected to a deliverywire to retrieve embolus.

Some common concerns of physicians who practice angioplasty include:concern that the thrombectomy device may capture an embolus, only tolose hold of it and accidentally deposit it in another area of theneurovasculature; concern that the device may not be able to capture a‘break-off’ piece of the embolus, which may migrate further into theneurovasculature; concern that the relatively large device may preventit from accessing and treating clots in small-diameter vessels; andconcern that the devices usually require adhesive joining or bondingbetween the delivery system and the treatment device. In the lattercase, in some instances a concern is that the adhesive bonding may fail,presenting the possibility that the pieces may separate, presenting aserious complication in the procedure.

SUMMARY

In one exemplary aspect, a thrombectomy device is disclosed. Thethrombectomy device includes a treatment portion, including areversibly-expandable framework configured to be deployed from within amicrocatheter into a selected vasculature for removing thrombus orembolus. The thrombectomy device further includes a substantiallytubular connection member disposed on a proximal end portion of thetreatment portion configured to receive a terminal portion of a deliverymember for positioning the treatment portion within the vasculature. Theframework includes structural features for engaging the thrombus orembolus including at least one of: framework peaks and valleys along along axis of the treatment portion; and a plurality of V-shaped strutmembers.

In one exemplary aspect, a device for removing an occlusion within abiological vasculature is described. The device includes a treatmentportion, including a substantially cylindrical, self-expandable cagecapable of being shifted between a compact delivery configuration and anexpanded treatment configuration. The self-expandable cage includes aplurality of interconnected, elongate-rectangular twisted cage strutsconfigured to form a series of substantially diamond-shaped repeat unitsalong a long axis of the cage in the expanded treatment configuration.Corners of the diamond-shaped repeat units are configured to capturinglyengage a portion of the occlusion for removal from the biologicalvasculature. When the cage is in the expanded configuration, proximaland distal end portions of the cage converge inwardly to formsubstantially close-ended proximal and distal cage end portionsrespectively. The system further includes a hollow catheter configuredfor delivering the treatment portion in the delivery configuration to anocclusion site within the biological vasculature.

In one embodiment, the system includes a tubular member disposed on theproximal cage end portion configured to receive a terminal end portionof a control wire for shifting the treatment portion from the compactdelivery configuration to the expanded treatment configuration.

In one embodiment, a distal end of one of the cage struts is twistedabout its long axis at least 170 degrees relative to a proximal end ofthe cage strut.

In one embodiment, struts of the treatment portion are configured toproduce a repeating wave pattern of strut crests and strut valleys whenviewed from a side perspective for maximizing increasing the likelihoodof securely engaging the occlusion for removal from the biologicalvasculature.

In one embodiment, the plurality of interconnected cage struts isconfigured in a substantially helical pattern between the close-endedproximal and distal cage end portions when the treatment portion is inthe expanded configuration. In a related embodiment, the wave patternhas a crest-to-valley distance of between about 0.1 mm and about 8.0 mm.In another related embodiment, the wave pattern has a crest-to-crestdistance of between about 0.5 mm and about 20 mm.

In one embodiment, the plurality of interconnected cage struts is coatedwith a pharmaceutical compound designed to aid in the removal of theocclusion from the biological vasculature.

In one exemplary aspect, a method of producing a device for restoringblood flow to an occluded blood vessel is described. The method includeslaser cutting a stock of a biocompatible material in a pattern that,when the material is formed into a substantially cylindrical shape, thematerial forms a self-expandable treatment portion capable of beingshifted between a compact delivery configuration and an expandedtreatment configuration. The treatment portion includes a cage formed ofa plurality of interconnected cage struts that form a series ofsubstantially diamond-shaped repeat units along a long axis of the cagewhen the treatment portion is in the expanded treatment configuration.The treatment portion includes a wave-like side profile having crestsand valleys formed by the plurality of interconnected cage struts,wherein the wave-like side profile has a crest-to-valley distance ofbetween about 0.1 mm and about 8.0 mm. Corners of the diamond-shapedrepeat units are configured to capturingly engage a portion of theocclusion for removal from the blood vessel.

In one embodiment, when the cage is in the expanded configuration, theproximal and distal end portions of the cage converge inwardly to form atubular connection member having a substantially solid, tube-shaped wallextending along a long axis of the treatment portion. In a relatedembodiment, the method further includes securing a distal portion of acontrol wire to the tubular connection member on the proximal endportion of the cage. In a related embodiment, the distal portion of thecontrol wire includes a substantially spherical plug member configuredto be urged through the tubular connection member against frictionalresistance provided by the interior surface of the substantially solid,tube-shaped wall, until the plug member emerges into the interior of thecage; and welding the plug member to the tubular connection member.

In one embodiment, the proximal and distal end portions comprise betweenabout one and about three of the substantially diamond-shaped repeatunits.

In one embodiment, the biocompatible material is Nitinol.

In one embodiment, at least one of the cage struts is twisted at least180 degrees about its long axis.

In one embodiment, the method further includes attaching a radiopaquematerial body to the treatment portion. In a related embodiment, theradiopaque material body extends from the proximal to the distal endportion of the treatment portion. In a related embodiment, theradiopaque material body is attached to the distal end portion of thetreatment portion.

In one embodiment, the method further includes treating the plurality ofinterconnecting strut members with an effective dose of a pharmaceuticalcompound designed to aid in the removal of the occlusion from the bloodvessel.

In one embodiment, the method further includes configuring at least oneof the strut members with a surface texture for increasing thelikelihood of fixedly engaging the strut member to a portion of theocclusion within a biological vasculature.

In one exemplary aspect, a thrombectomy device is disclosed. The deviceincludes an elongate catheter configured to house a deployable basketmember that is capable of reversibly shifting from a compactconfiguration to an expanded configuration as the basket member is urgedout of a distal end portion of the catheter. A deployment member spansfrom a distal end portion of the basket member to a proximal end portionof the catheter so as to be manipulable by a practitioner to control thedeployment of the basket member within a vasculature. An arcuate wiremember spans opposite sides of a substantially spearhead-shaped, wirebase, and is configured such that the arcuate wire member and thespearhead-shaped base have a substantially perpendicular relationshipwhen the basket member is in the expanded configuration.

DESCRIPTION OF DRAWINGS

The present embodiments are illustrated by way of the figures of theaccompanying drawings which are not necessarily to scale, in which likereferences indicate similar elements, and in which:

FIG. 1 is a treatment portion of a thrombectomy device according to oneembodiment;

FIG. 2 is a treatment portion of a thrombectomy device according to oneembodiment;

FIG. 3 is a magnified view of the thrombectomy device illustrated inFIG. 2;

FIG. 4 is a treatment portion of a thrombectomy device according to oneembodiment;

FIG. 5 is a treatment portion of a thrombectomy device according to oneembodiment;

FIG. 6 is a treatment portion of a thrombectomy device having anon-traumatic tip according to one embodiment;

FIG. 7 illustrates connectivity between a treatment portion and adelivery wire in a thrombectomy device according to one embodiment;

FIG. 8 is a thrombectomy device according to one embodiment;

FIG. 9 is a thrombectomy device including a marker wire according to oneembodiment;

FIG. 10 is a thrombectomy device according to one embodiment;

FIG. 11 is a thrombectomy device according to one embodiment;

FIG. 12 is a thrombectomy device according to one embodiment;

FIG. 13 is a thrombectomy device formed from braided wire, according toone embodiment;

FIG. 14 is a thrombectomy device according to one embodiment;

FIGS. 15A and 15B illustrate cut-patterns for making a treatment portionof a thrombectomy device according to one embodiment;

FIGS. 16A-16D illustrate a method for using a thrombectomy device toremove a thrombus from a blood vessel according to one embodiment; and

FIGS. 17A-17G illustrate a thrombectomy device according to oneembodiment and a method of its use.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In one exemplary aspect, systems and methods for removing thrombus orembolus in a biological vasculature are disclosed to provide thecapability of restoring blood flow in an acute ischemic stroke patient.As is well known in the medical arts, timely removal of thrombus orembolus in stroke patients can be a critical survivability factor. Invarious illustrative embodiments disclosed herein, a mechanicalthrombectomy device can include a delivery portion configured to allowselective placement of an expandable treatment portion into a chosensite within a biological vasculature so as to allow the removal orretrieval of an embolus or thrombus.

In one illustrative embodiment described more completely below, thedelivery portion can be fabricated from a single wire source or,alternatively, from multiple wires. The expandable treatment portion canbe cut, e.g., laser cut from a small section of tubing of appropriatematerial and subsequently heat treated to form a desired shape; or, inanother approach the expandable treatment portion can be cut and formedfrom braided wires into the configurations as illustrated herein.

In one embodiment, the expandable treatment portion of a thrombectomydevice can be configured to improve clot retention during removal of athrombus or embolus from a biological vasculature. For example, theexpandable treatment portion can be configured as a substantiallytubular, basket-like framework having peaks and valleys between strutand frame members, as described more fully herein, and can also includeat least one tapered, closed end which can facilitate effective and saferemoval of thrombus or embolus from a selected vasculature.

In one embodiment, the proximal, distal, or proximal and distal portionsof the expandable treatment portion framework can include V-shaped strutjoints to assist in engaging a clot within a blood vessel. In variousembodiments, one or more bio-agents, pharmaceutical compositions,medicines, or the like can be coated on, attached to, or otherwiseincorporated with the treatment portion to assist in dissolving orsoftening clots for removal. In one embodiment, the treatment portioncan include a radiopaque material to assist a practitioner invisualizing the placement of the treatment portion in a selectedlocation within a blood vessel, e.g., using fluoroscopic imaging. In oneembodiment, the surface of the expandable treatment portion can beconfigured to enhance embolus or thrombus affinity by, e.g., coating thesurface with a selected affinity substance or configuring the texture ofthe treatment portion to adhere to the embolus or thrombus by mechanicalor chemical methods.

Referring now to the figures, wherein like references indicate similarelements throughout, various embodiments of a thrombectomy device areillustrated. In the discussion that follows, reference is made to one ormore “treatment portions” which, for the purpose of this disclosure,generally refer to portions of the thrombectomy device that areconfigured to engage a thrombus or embolus for the purpose of effectingits removal from a selected portion of an animal (including human)vasculature. Certain figures may illustrate only certain features orparts of the thrombectomy device exclusively for the purpose ofhighlighting their particular configuration or use. It should beunderstood, however, that such features or parts can be incorporatedinto, or assembled as a part of an overall working thrombectomy devicecapable of being used in a surgical setting by physicians, surgeons, andthe like. Similarly, various treatment portion embodiments describedherein can be interchangeable with other elements of a thrombectomydevice. For example, treatment portions having different dimensions canbe reversibly attached to a guidewire, which, in general can be used inmanipulating the treatment portion in proximity to thrombus or emboliwithin a vasculature.

Referring now to FIG. 1, a reversibly-expandable treatment portion(hereinafter “treatment portion”) 100 of a thrombectomy device is shownaccording to one embodiment. In this and other embodiments, thetreatment portion 100 is capable of being housed in, and reversiblydeployed from a delivery device such as a microcatheter which can beused to deliver the treatment portion to the general area of a thrombusor embolus. In this and other embodiments, the treatment portion iscapable of collapsing to a minimum volume so that it can be containedwithin the delivery device, e.g., a microcatheter (not shown in FIG. 1).In this embodiment, the treatment portion 100 includes a tubularproximal end portion 105 that extends into a framework body 115, and adistal end 110 that, in this embodiment, is an open terminus of theframework body 115. In this and other embodiments, the treatment portion100 is configured in size and shape so as to be cooperatively used witha microcatheter to deliver the treatment portion 100 to a selected areaof a biological vasculature, e.g., the location of a thrombus orembolus. In one embodiment, the proximal end portion 105 can be joinedor coupled with a delivery member as described more fully herein.

In this embodiment, a plurality of interconnected struts, e.g., strut122 and 124, connect the proximal end portion 105 to the framework body115 as illustrated. In this and other embodiments, the tapered portion120 can be engaged with a thrombus or embolus during extraction from avasculature region. For example, the treatment portion 100 can be placedat a selected location near the thrombus or embolus within avasculature. The treatment portion 100 can be positioned, e.g., by aphysician, such that the tapered portion 120 first engages the thrombusor embolus during extraction from the vasculature as described ingreater detail below. In this embodiment, the leading edges of thetapered portion 120, e.g., struts 122 and 124 can form engagementsurfaces of a radially-expanding cage for engaging a thrombus or embolusperpendicular to the long axis of the treatment portion 100.

In this embodiment, the framework body 115 is formed of a plurality ofsubstantially diamond-shaped framework repeat units, e.g., repeat unit126, which are formed from interconnected struts; e.g., struts 122, 124,etc. In various embodiments, the number of circumferential repeat unitscan, without limitation, range from about two to about ten, and thenumber of linear repeat units, e.g., repeat units substantially alignedalong the long axis of the treatment portion 100 can, withoutlimitation, range from about one to about twenty. It should beunderstood that the number of circumferential or linear repeat units canbe selected according to preference, function, or other considerations.

In one embodiment, the cross-sectional diameter of the distal end 110can be equal to, larger than, or smaller than the cross-sectionaldiameter of the framework body 115 according to preference, function, orother considerations. For example, the cross-sectional diameter of thedistal end 110 can be greater than the cross-sectional diameter at theapproximate center of the framework body 115. In such a configuration,the larger-diameter end of the framework body 115 can assist in catchingthrombus or embolus fragments that may break off as the treatmentportion is engaged with the clot. In such an embodiment, the struts ofthe framework body 115 at or near the distal end 110 can be configuredto minimize the likelihood of damage to the walls of the vasculaturefrom contact. For example, the distal end struts can be smooth, ortapered so as to reduce the likelihood of tearing veins or arteries asthe treatment portion is shifted therethrough.

In some embodiments, the size of the repeat units 126 can be homogeneousthroughout the treatment portion 110; in other embodiments however, thesize, shape, or size and shape of the repeat units 126 can vary. In oneembodiment, the size and shape of the various repeat units 126 can varyso as to increase the likelihood of contact and retention of a thrombusor embolus, including parts, fragments, or pieces thereof. In someembodiments, the struts of the framework body 115 can have a selectedamount of twist to improve adhesion and engagement with a thrombus orembolus. For example, considering a single diamond repeat unit (e.g.,repeat unit 126), in such an embodiment, one or more sides of thediamond repeat unit can include a twisted strut.

In this embodiment, the repeat units of the framework body 115 includeV-shaped portions, e.g., V-shaped portions indicated by referencenumeral 130 in FIG. 1. These structures can also assist to engage andretain a clot during a thrombectomy procedure and can minimize thelikelihood that the clot is disengaged or lost during retrieval.

Referring now to FIG. 2, an expandable treatment portion 200 is shownaccording to one embodiment. In this embodiment, the treatment portion200 includes proximal (205) and distal (210) end portions that eachinclude a tubular portion similar to end portion 105 in FIG. 1, andtapered sections 207, 208, respectively that transition into a frameworkbody 215 formed from struts, e.g., struts 222, 224, etc. In thisembodiment, when viewed from a side perspective as illustrated in FIG.2, the framework body 215 includes crests, e.g., crest 230, and troughs,e.g., trough 235 which are collectively formed by the arrangement of thevarious struts, as illustrated.

The wave-like pattern of the struts as noticed particularly from a sideelevational view can include a repeating crest-to-crest length analogousto a wavelength or wave cycle. In this and other embodiments, the strutsof a treatment portion can be configured so as to create a desiredwave-like pattern according to preference. In this and otherembodiments, the wave-like features of the treatment portion 200 can beselected so as to create a treatment portion that maximizes engagementwith an embolus or thrombus. For example, in one embodiment, a treatmentportion can be configured to have an exterior wave-like pattern wherethe crest-to-trough distance is between about 0.1 mm and about 8 mm, andthe distance between crests (e.g., the wavelength) is between about 0.5mm and about 20 mm.

In this and other embodiments, the treatment portion 200 can include oneor more twisted strut members having a twisted or torsionalconfiguration about the long axis of the strut that extends a selectedlength along the long axis of the treatment portion 200. A twisted strutmember can be, e.g., strut 222, strut 224, or other strut members of thetreatment portion 200. Without wishing to be bound by theory, it isbelieved that the likelihood of engagement between the treatment portion200 and a thrombus or embolus is increased due to the complex shape of atwisted strut member compared to a strut member having an untwisted ornon-torsional configuration.

In this and other embodiments, a treatment portion can include twistedstrut members at desired locations to maximize gripping interaction witha thrombus or embolus. For example, a treatment portion can include oneor more twisted strut members as part of a tapered end of the treatmentportion, e.g., tapered portion 120 of treatment portion 100 (FIG. 1). Inanother example, the entire treatment portion can be formed of twistedstrut members.

In this embodiment, the closed, tapered ends 205, 210 of the frameworkbody 215 can assist in catching particles that may break off from a mainthrombus or embolus body and act as a basket to reduce the likelihoodthat these particles can be undesirably transported by bodily fluids(such as blood) to other areas of the vasculature. In this embodiment,the framework body 215 includes repeat units similar to that describedwith respect to FIG. 1. The peaks and valleys formed by the struts andthe cell spacing in this embodiment can improve engagement with a clotand reduce the likelihood that the clot will disintegrate as it is beingretrieved through the vasculature.

FIG. 3 is a magnified view of a proximal end of a framework body, e.g.,proximal end portion 105 of framework body 115 according to oneembodiment. It should be understood that the view shown in FIG. 3 can beapplicable to embodiments other than that described with respect toFIG. 1. FIG. 3 illustrates a twisting pattern of the struts, e.g.,struts 122, 124 beginning at each joint where the struts interconnect,e.g., at joints 150 and 155. Such a strut configuration can assist ineffective thrombus or embolus removal in that it can provide a varyingsurface topology throughout the framework body for engaging a thrombusor embolus. In this embodiment, the tubular end segment of the proximalend 105 can be used to join the treatment portion 100 with a deliveryportion (not shown in FIG. 3) or used in an assembly of radiopaqueelements for visualizing the position of the framework body 100 within avasculature.

FIG. 4 is a perspective view of a treatment portion 400 according to oneembodiment. In this embodiment, the framework body 408 includes strutmember arranged in a substantially spiraled configuration. For example,elongate strut members 415 and 420 extend from proximal (405) to distal(410) ends of the framework body 408 in a substantially-alternatingspiraled arrangement. Such a configuration can facilitate smooth andsafe delivery of the treatment portion 400 to the treatment area as wellas effective clot engagement and retention. In this embodiment,treatment portion 400 can be used particularly in cases where apatient's vasculature is known to be fragile and thrombus or embolusremoval may dictate extra caution.

Referring now to FIG. 5, a perspective view of an expandable treatmentportion 500 is shown according to one embodiment. In this embodiment,the expandable treatment portion 500 can be similar in construction to,e.g., the treatment portion 100 or 200 described with respect to FIG. 1or 2 respectively, and includes proximal (505) and distal (510) endportions, a distal tapered portion 507, a proximal radiopaque marker 515and a distal radiopaque marker 520. The treatment portion 500 includes aplurality of twisted struts, e.g., strut 540, configured so as to formvalleys 525 and peaks 530 along the long axis of the treatment portion.In this embodiment, the treatment portion 500 includes a marker wire 535spanning proximal and distal end portions 505, 510 respectively forimproved radiopacity. Treatment portions having radiopaque markers canbe incorporated into any treatment portion embodiment described herein,including equivalents and modified versions thereof.

FIG. 6 is a magnified view of the distal portion 510 of the treatmentportion 500 in FIG. 5, according to one embodiment. In this embodiment,the strut members of the treatment portion 500, e.g., strut members 508,509 extend from a tubular end member 550 in a graduallyradially-expanding configuration to the elongate, substantiallytubular-shaped framework body 557. In some embodiments, the strutmembers 508, 509 may be independent strut members that span the endmember 550 and the framework body 557; in other embodiments, theconfiguration and orientation of the strut members 508, 509 cangradually transition from a tapered configuration in the tapered portion507 to a substantially un-tapered configuration as part of the frameworkbody 557. In some embodiments, the struts that together form theframework body 557 can be twisted, e.g., strut member 660. As with otherembodiments, tapered strut members can assist in clot removal boththrough providing a complex surface with which to engage a clot, and inretaining clot fragments that may break off during clot removal ortransportation throughout the vasculature. A trauma-reducing tip 555,formed in this example of a spiraled radiopaque material can be used fornavigating and positioning the treatment portion by a practitioner. Inthis embodiment, the device body, e.g., the tubular-shaped framework 557in this embodiment includes a plurality of repeat units as describedheretofore, e.g., with respect to FIG. 1. In this and other embodiments,the cell width (denoted w in FIG. 6) can vary from about 1.5 mm to about10 mm, although the cell width can be configured to any desired value;in this and other embodiments, the cell length (denoted l in FIG. 6) canvary from about 1.5 mm to about 12 mm, although the cell length cansimilarly be configured to any desired length value.

Referring now to FIG. 7, a distal portion of a thrombectomy device 700is illustrated according to one embodiment. In this embodiment, thedevice 700 includes a treatment portion as described heretofore, e.g.,treatment portion 500 as described with respect to FIG. 5, incooperative assembly with a distal portion of a delivery wire. In thisexample, reference to treatment portion 500 from FIG. 5 is made,however, it will be understood that other treatment portion embodimentscan be substituted in the description that follows.

In this embodiment, an elongate delivery wire 701 includes a bulbousterminal portion 702 configured to prevent the treatment portion 500from being removed from the delivery wire 701 under normal surgicaloperating conditions. For example, the treatment portion can beconfigured to not disengage from the delivery wire 701 as the treatmentportion is being used to extract a thrombus or embolus. The bulbousportion 702 can be formed on the tip of the delivery wire by, e.g.,thermal heating from a laser after the terminal end of the delivery wire701 has been advanced through the tubular proximal end 505 of thetreatment portion. In one non-limiting approach, a thrombectomy device700 can be assembled by sliding the treatment portion 500 onto thedelivery wire 701 until it reaches a step portion 705 positioned at aselected distance from the terminal portion of the delivery wire 701.The terminal portion of the delivery wire can then be heated to form thebulbous portion as described and to weld the treatment portion 500 tothe delivery wire 701. In other embodiments, the treatment portion 500can be secured to the delivery wire by adhesives or glue. In yet anotherembodiment, a piece of radiopaque material can be welded onto the distalend of the delivery wire 701 to form a larger profile at the distal endand subsequently mechanically lock the delivery wire in position. Aproximal radiopaque marker 710 such as a marker band, marker coil, orradiopaque cover or coating can be assembled and applied to the distalend of the delivery wire as illustrated.

Combining elements from multiple embodiments described herein, FIG. 8shows a side elevational view of a portion of the assembled thrombectomysystem 700 according to one embodiment, including the distal end of thedelivery wire 701, proximal maker 710, expandable treatment portion 500,and distal marker/non-traumatic tip 555.

FIG. 9 shows a side elevational view of an exemplary thrombectomy device900 including various components as described herein, including a markerwire 535 that spans the length of the treatment portion 500 for fulllength visualization using radiographic techniques, for example; anexpandable treatment portion 500, including peaks 530 and valleys 525thereof; proximal (508) and distal (507) tapered portions; and adelivery wire 701. In this embodiment, the delivery wire 701 includes ataper in the proximal delivery portion to provide a connection betweenthe delivery wire 701 and the treatment portion 500 having a desiredamount of stiffness.

Referring now to FIG. 10, a braided, reversibly-expandable treatmentportion 1000 is shown according to one embodiment. The treatment portion1000 can be attached to, e.g., a delivery wire 1001 as described herein,and used as part of a thrombectomy device. The proximal end 1005 of theelongated delivery portion 1001 can be fabricated from single wire ormultiple wires. If the treatment portion is fabricated from multiplewires, the wires can be the same wires to form the distal expandableportion 1000 of the device system. In this embodiment, the multiplewires 1031, 1032, 1033 at the proximal delivery portion can be twistedtogether tightly to form a small profile for easy delivery. Thestiffness can vary from the proximal delivery portion across the wholetreatment portion; in other words, the treatment portion can have afirst stiffness at the proximal end, and a second, different stiffnessat the distal end 1020.

A radiopaque marker 1010 can be attached to any part of the treatmentportion or delivery wire to aid a practitioner in positioning within avasculature; in this embodiment, the radiopaque marker 1010 is attachedto a distal portion of the delivery wire 1001. One or more wires in thedevice can be made from radiopaque material. In this embodiment, aradiopaque marker, e.g., marker 1021 is attached to each terminus ofwire, as illustrated. The distal end of the treatment portion can beopen (with or without struts in the lumen) and can have differentdiameter than the main body with either a flare or taper.

FIGS. 11, 12, and 13 illustrate various alternative treatment portionembodiments of a thrombectomy system as generally described herein. Forexample, FIG. 11 shows a side-elevational view of a thrombectomy system1100 with a braided expandable portion 1110 according to one embodiment.The proximal elongated delivery portion 1120 can be fabricated fromsingle wire or multiple wires. If multiple wires are used, the wires canbe the same wires that form the distal expandable portion of the system1100. The distal end 1130 of the expandable portion 1100 can have taperand soft tip with a radiopaque marker 1140 if desired. In thisembodiment, the proximal delivery portion has a smaller diameter whilethe expandable treatment portion has a larger diameter, although otherconfigurations can be used.

FIG. 12 shows a side-elevational view of a thrombectomy system 1200according to one embodiment, which has a braided expandable portion 1210with a marker wire 1230 that spans proximal (1240) and distal (1250) endportions. The proximal elongate delivery portion 1260 can be made from,e.g., single wire or multiple wires. If multiple wires are used, thewires can be the same wires with that form distal expandable portion ofthe system 1200. The distal end 1250 of the expandable portion can havea taper and soft tip with a radiopaque marker 1270 if desired.

FIG. 13 shows a side-elevational view of a portion of a thrombectomysystem 1300 system having a braided expandable portion 1320 according toone embodiment. In this embodiment, a proximal elongated deliveryportion 1305 can be made from, e.g., single wire or multiple wires. Ifmultiple wires are used, the wires can be the same wires to form theexpandable portion 1320 of the system. The expandable portion 1320 canhave proximal (1315) and distal (1317) taper portions and a soft-tipradiopaque marker 1325 if desired. In this embodiment, a lumen is formedin the proximal delivery portion 1305 as illustrated; heat shrink tubing1350 or a polymer cover can be used to form the interface between thelumen 1305 and the expandable portion 1320. In this embodiment, theproximal delivery portion can have variable stiffness along the length.

Referring now to FIG. 14, a portion of a thrombectomy device 1400incorporating various elements from embodiments described herein isshown according to one embodiment. In this embodiment, the treatmentportion can be made from a wire providing variable stiffness along itslength. In this embodiment, the diameter of the expandable treatmentportion is substantially the same across its length; however, thediameter can vary along the length in alternative embodiments. In thisembodiment, the distal end 1407 of the expandable treatment portion isbe tapered to increase the likelihood of retaining any fragments of athrombus or embolus that break off during extraction from a vasculaturesite. In this embodiment, a soft, non-traumatic tip made from radiopaquematerial 1410 is attached to the distal end 1407 of the delivery portion1405. In this embodiment, the device treatment portion 500 can befabricated from Nitinol super elastic material, Nitinol shape memoryalloy tubing, or any other biocompatible material that exhibits superelastic or shape memory properties. In one embodiment, the treatmentportion 500 can be fabricated using laser cutting, mechanical machining,chemical machining, electrochemical machining, EDM, or other methods.The delivery wire 1405 can be made either from single wire or multiplewires components as described herein, for example. In one embodiment,the delivery wire 701 can have variable stiffness along its length tofacilitate smooth delivery and easy retrieval of the device.

A radiopaque marker 555 (marker band, marker coil, marker wire, markercoating, or other marker) can be attached at the proximal 1405 anddistal 1407 ends of the treatment portion 500 to help with devicepositioning. In this embodiment, the treatment portion is configuredwith a plurality of peaks and valleys as heretofore described to improveclot adhesion and retrieval. For example, the peak and valleys along thelength of the treatment portion 500 can cooperatively engage and retainthe clot volume and reduce the amount of force necessary to remove theclot from a vasculature, e.g., to prevent the clot from breaking. Inthis embodiment, the strut(s) of the device treatment portion e.g.,struts 508 and 509 can be arranged at an angle from about 5 degrees toabout 175 degrees from the longitudinal axis of the device. In thisembodiment, the plurality of struts that form the treatment portion 500can be twisted to improve clot affinity and retention during athrombectomy or embolectomy procedure. In this embodiment, the surfacesof the plurality of struts can be modified by chemical or physicalmethods, e.g., mechanical surface roughness modification, chemicaletching, PVD, CVD, surface coating, micro pinning, or other techniquesfor improved clot retention and retrieval.

In this and other embodiments, the dimensions of the system can bechosen and configured according to preference or to meet desiredperformance characteristics. For example, referring to FIG. 14, thetotal length l_(t) of the treatment portion (including the taperedportions) can be varied to accommodate different sizes and shapes ofvasculature or target thrombi or emboli; the effective length l_(tp) ofthe treatment portion 500, the length l_(d) of the delivery wire, thelength l_(r) and diameter d_(r) of the radiopaque marker, the diameterof the delivery wire d_(w), the length of the distal tip l_(tip), thediameter of the treatment portion d_(tp), and any other aspect of thethrombectomy device 1400 can each be independently varied or modifiedfrom that described and illustrated herein to provide certain advantagesor to meet desired performance characteristics.

In various embodiments, the proximal delivery portion can be formedfrom, for example, Nitinol wire or stainless steel wire having adiameter between about 0.005 inches and about 0.060 inches, althoughother materials can be substituted. In some embodiments, the length ofwire in a thrombectomy device (e.g., device 1400 in FIG. 14) can vary,e.g., from about 60 em to about 200 cm. In some embodiments, thediameter of the tapered portions, e.g., tapered portion 120 in FIG. 1can be, e.g., from about 0.005 inches to about 0.055 inches. In variousembodiments, the aforedescribed radiopaque markers can be made from,e.g., Pt, Pt—Ir alloy, W, Ta, or other radiopaque materials. In someembodiments, the length of the tapered portion, e.g., tapered portion120 in FIG. 1 can be, e.g., from about 10 mm to about 150 cm. In variousembodiments, a proximal marker can be in the form of, e.g., a markerband, or marker coil, or a polymer extrusion having a loaded radiopaquematerial. In some embodiments, the length of the radiopaque marker canbe, e.g., from about 0.5 mm to about 100 mm. In some embodiments, thediameter of the marker can vary, e.g., from about 0.005 inches to about0.060 inches. In some embodiments, the treatment portion can be fromabout 8 mm to about 80 mm. In some embodiments, the diameter of thetreatment portion can be, e.g., from about 1.5 mm to about 12 mm. Insome embodiments, the struts have a strut thickness of between about 20μm and about 200 μm.

Referring now to FIGS. 15A and 15B, laser cut patterns for producing atreatment portion of the type described herein are illustrated accordingto one embodiment. In this embodiment, which can be a manufacturingmethod, the treatment portion can, after being laser cut, be heattreated and expanded to its final diameter as is known in the art; asurface treatment can optionally be applied thereafter to providedesired strut surface characteristics for engaging and retaining clotsof various type within a vasculature. In one embodiment, a mandrel canbe used to apply a desired amount of twist to the struts to form atreatment portion framework having twisted struts as described herein,e.g., treatment portion 200 described with respect to FIG. 2. The lasercut patterns shown in FIGS. 15A and 15B can produce a treatment portionas illustrated in FIG. 14.

Referring now to FIGS. 16A-16D, a method for using a thrombectomy deviceas described herein is disclosed according to one non-limitingembodiment. It will be understood that the following example is one ofmany methods that may be used to treat patients having a thrombus orembolus, e.g., a stroke patient, and the chosen treatment can beselected and/or modified by a physician as he deems necessary.

First, referring to FIG. 16A, a suitable guidewire (not shown in FIGS.16A-16D) can be advanced through the vasculature to the location of thethrombus 1601. The guidewire can be inserted through the thrombus 1601as is generally known in the art. A microcatheter 1615 can be advancedalong the guidewire until it has extended through the thrombus 1601 adesired amount, as illustrated. In some methods, fluoroscopic imagingcan aid the practitioner in the proper placement of the guidewire andthe microcatheter 1615. Next, while maintaining the position of themicrocatheter 1615, the guidewire can be withdrawn through themicrocatheter 1615.

A treatment portion 1630 of a thrombectomy device, such as any of thetreatment portions described herein, can be advanced through themicrocatheter 1615 until its distal tip 1632 reaches approximately thedistal end 1617 of the microcatheter 1615. As generally describedherein, the treatment portion can include a delivery wire, e.g.,delivery wire 701 coupled to the treatment portion, e.g., treatmentportion 100. As previously disclosed, the treatment portion can includemarkers of any suitable type which can aid the practitioner in properplacement relative to the thrombus 1601. In one approach, the distal end1632 of the treatment portion 1630 can be advanced beyond the thrombus1601 to ensure that an adequate amount of the treatment portion engagesthe clot. In another approach, the distal end of the treatment portion1630 can be positioned so that when the microcatheter 1615 is retracted,the treatment portion 1630 expands substantially within the thrombus1601 as illustrated in FIGS. 16A-16D. In yet another approach, thetreatment portion can be advanced past the thrombus so that the proximalend 1633 of the treatment portion engages the thrombus as it isretracted from the vasculature, e.g., in the direction of the arrow inFIGS. 16B-16D.

Next, referring to FIGS. 16B-D, the practitioner can stabilize theposition of the treatment portion 1630 via the delivery wire whileretracting the microcatheter 1615. In this embodiment, as themicrocatheter 1615 is withdrawn, the treatment portion of thethrombectomy device expands, thus engaging the thrombus 1601 in andthroughout the framework of the treatment portion. Finally, thetreatment portion can be withdrawn together with the microcatheter fromthe vasculature and out of the body, carrying the thrombus with it.

Referring now to FIGS. 17A and 17B, a thrombectomy device 1700 isillustrated according to one non-limiting embodiment. FIG. 17Aillustrates a reversibly-deployable and expandable basket member 1710 ofthe thrombectomy device 1700 in a partially-expanded configuration, andFIG. 17B illustrates the basket member 1710 in a fully-expandedconfiguration. In this embodiment, the device 1700 includes a deliverycatheter 1701 which is configured so as to fit, and be maneuverablewithin a selected vasculature. It should be understood that the catheter1701 and the other components of the device 1700 can be configured toaccommodate use in a variety of vasculature shapes and sizes. Similarly,the catheter 1702 can be flexible so as to allow propagation of thedistal tip 1717 to a selected region within a vasculature.

In this embodiment, the basket member 1710 can be reversibly deployedfrom within the catheter 1701 by shifting a wire deployment member 1730which is coupled to the basket member 1710 at a distal end portion 1702.In this embodiment, the deployment member 1730 spans from the distal endportion 1702 to a proximal end portion of the catheter (not illustrated)and is configured to be manipulable by a practitioner to controldeployment of the basket member 1710 from the distal end of the catheter1717, e.g., as illustrated in the series of illustrations in FIGS.17C-17G.

In this embodiment, a reversibly-expandable cage portion 1720 of thebasket member 1710 can expand between compact and extendedconfigurations. In this embodiment, a compact configuration can be onein which the cage portion 1720 is housed within the catheter 1701 andcorrespondingly occupies a minimum volume. An expanded configuration canbe one in which the cage portion 1720 is extended outside of thecatheter 1701 and expands such that the opening of the basket, definedsubstantially by arcuate wire member 1725, fills the cross-sectionaldiameter of the blood vessel as illustrated in FIGS. 17C-17G.

In this embodiment, the cage portion 1720 extends from the arcuate wiremember 1725 toward the distal end portion 1702 as illustrated. In thisembodiment, the base of the basket 1710 is defined by wire member 1705.When the basket member 1710 is in an extended configuration, wire member1705 assumes a spear point shape, where the wire 1705 comes to a pointat the distal end 1702 along a centerline of the elongate axis, e.g.,parallel with deployment member 1730.

Device 1700 can be particularly beneficial for removing thrombus oremboli while reducing the likelihood of releasing fragments that canlater become nuclei for the formation of downstream clots. Referring nowto the FIGS. 17C-17G, a method of using the device 1700 is illustratedaccording to one embodiment. In FIG. 17C, a distal portion 1717 of thedelivery catheter 1701 is advanced in an artery 1750, e.g., under thecontrol of a physician, to an area substantially adjacent to an arterialthrombus or embolus 1790. Next, referring to FIG. 17D, the basket member1710 can be advanced under, around, or through the thrombus or embolus1790 by controlled shifting of the deployment member 1730, again, forexample, under the direction or control of a physician.

Next, referring to FIG. 17E, the cage portion 1720 can be expanded suchthat arcuate wire member 1725 has a diameter suitable to surround all,or most of the thrombus 1790. In general, the cage portion 1720 can becontrollably expanded by a practitioner. In some cases, the cage portion1720 can be expanded such that the arcuate wire member 1725 confrontsthe inner wall of the artery substantially along its arcuate length. Ina preferred method, radiographic techniques can be used to verify thatthe distal end 1717 and the cage portion 1720 pass the thrombus 1790 toensure full capture prior to removal. Once the cage portion 1720 isexpanded, the delivery catheter 1701 and the basket member 1710 can besynchronously shifted in a direction to withdraw the device 1700 fromthe patient (FIG. 17F). As the catheter 1701 is being withdrawn, thebasket member 1710 can be shifted to a closed configuration, illustratedin FIG. 17G to fully capture the thrombus 1790 within the basket member1710. In one embodiment, the catheter can be configured so as to allowthe basket member 1710 to be drawn therewithin, including the thrombus1790, while it is being removed from the patient.

In this embodiment, the closed portion of the basket member 1710 at thedistal end portion 1702 can reduce the likelihood of the thrombus orembolus ‘escaping’ during removal, and similarly increase the likelihoodof capturing any thrombus or embolus fragments that may break off of themain body during removal.

A number of illustrative embodiments have been described. Nevertheless,it will be understood that various modifications may be made withoutdeparting from the spirit and scope of the various embodiments presentedherein. For example, a thrombectomy device as described herein caninclude other components and features that enable the treatment portionof the device to be used as generally described herein. For example,certain controls configured for use by a physician to guide thetreatment portion can be incorporated. While not illustrated in thefigures, it should be understood that the various treatment portions anddelivery wires attached thereto can be controlled by hand, robot, orother means for positioning and extracting clots from vasculature. Fiberoptic visualization components for feeding the treatment portion to itsintended location or for assisting in clot removal can similarly beincorporated into a thrombectomy device. In one example, pharmaceuticalcompounds, including clot-reducing or softening compounds can beintroduced to a clot site through the delivery wire. Any of the deviceembodiments described herein, including modifications thereof, can beappropriately sized so as to be capable of being loaded into a deliverycatheter (for example, a microcatheter), and delivered to a targetlocation in a vessel to retrieve a clot. A device of the type describedherein can have a surface treatment on various portions thereof toimprove performance or to satisfy other device requirements for use. Forexample, any portion of a thrombectomy device can be coated or coveredby a biocompatible material to provide lubrication entirely orpartially. The surface of the distal treatment portion can have apositive or negative charge for improved clot adhesion. The surface ofthe distal treatment portion can also be mechanically or chemicallytreated to have a rough surface for improved clot adhesion. The roughsurface can be achieved by, e.g., 1) providing a porous surface coatingor layer; 2) microblasting or micropinning one or more surfaces of thethrombectomy device; or 3) providing an irregular strut geometry orarrangement, for example, providing twisted struts or struts withvarying angles. Accordingly, other embodiments are within the scope ofthe following claims.

What is claimed is:
 1. A method of producing a device for restoringblood flow to an occluded blood vessel, comprising: cutting a stock of abiocompatible material in a pattern that, when said material is formedinto a substantially cylindrical shape, said material forms aself-expandable treatment portion capable of being shifted between acompact delivery configuration and an expanded treatment configuration;wherein said self-expandable treatment portion comprises a cage formedof a plurality of interconnected cage struts that form a series ofsubstantially diamond-shaped repeat units along a long axis of said cagewhen said self-expandable treatment portion is in said expandedtreatment configuration; wherein said self-expandable treatment portioncomprises a wave-like side profile having crests and valleys formed bysaid plurality of interconnected cage struts, wherein said wave-likeside profile has a crest-to-valley distance of between about 0.1 mm andabout 8.0 mm; wherein corners of said diamond-shaped repeat units areconfigured to capturingly engage a portion of said occlusion for removalfrom said blood vessel; wherein, when said cage is in said expandedtreatment configuration, a proximal end portion of said cage convergesinwardly to form an elongate tubular connection member extendingoutwardly and substantially coaxially with a long axis of saidself-expandable treatment portion; forming a bulbous terminal portion ona terminal end portion of a delivery wire after said terminal endportion has been advanced through said tubular connection member;attaching said bulbous terminal portion to said tubular connectionmember within the interior of said self-expandable treatment portion;and attaching a radiopaque material body proximal to said proximal endportion of said self-expandable treatment portion.
 2. The method ofclaim 1, wherein said proximal and distal end portions comprise betweenabout one and about three of said substantially diamond-shaped repeatunits.
 3. The method of claim 1, wherein said biocompatible material isNitinol.
 4. The method of claim 1, wherein at least one of said cagestruts is twisted at least 180 degrees about its long axis.
 5. Themethod of claim 1, wherein said radiopaque material body extends fromsaid proximal to said distal end portion of said self-expandabletreatment portion.
 6. The method of claim 1, further comprising treatingsaid plurality of interconnecting strut members with an effective doseof a pharmaceutical compound designed to aid in the removal of saidocclusion from said blood vessel.
 7. The method of claim 1, furthercomprising configuring at least one of said strut members with a surfacetexture for increasing the likelihood of fixedly engaging said strutmember to a portion of said occlusion within a biological vasculature.